JP7176906B2 - Adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

Conventionally, in a pressure-sensitive adhesive sheet that is attached to an adherend via a pressure-sensitive adhesive layer, for example, as disclosed in Patent Document 1 and Patent Document 2, a release sheet (release liner) may be provided with an embossed pattern.

Since such an embossed pattern is reversed to form, for example, grooves in the adhesive layer, when the adhesive sheet is applied to an adherend, air trapped between them is discharged through the grooves of the adhesive layer. , the swelling of the adhesive sheet is suppressed.

Suppression of blistering enables clean attachment of the adhesive sheet, and is therefore particularly preferable for decorative sheets, such as blackout tapes attached to window frames of vehicle bodies, where design is important.

In addition, in order to attach the adhesive sheet to the adherend cleanly, it is important to prevent swelling and to align the adhesive sheet to the adherend. , it becomes easy to perform by temporarily fixing through the exposed part of the adhesive layer.

In this case, the release liner is cut by pressing a blade against the release liner surface of the adhesive sheet so that the release liner can be partially peeled off. Here, the side of the release liner against which the blade is pressed is the opposite side to the side adjacent to the adhesive layer. It is usually disturbed so as not to cause blocking which makes it difficult to separate.

Retable 2003/025078 JP 2010-180271 A

However, if the release liner has unevenness like the embossed pattern of the prior art on the surface adjacent to the pressure-sensitive adhesive layer, and the opposite surface is roughened to include undulations of large amplitude, the thickness varies depending on the location. , and there is a possibility that it may be difficult to cut the release liner at an appropriate depth.

If the cut is made too deep by mistake, the appearance of the PSA sheet may be impaired by the marks left by the cut. Therefore, it is not preferable.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive sheet in which a release liner can be easily cut at an appropriate depth.

To achieve the above object, the pressure-sensitive adhesive sheet of the present invention comprises a protective layer, a coat layer, a substrate layer, a pressure-sensitive adhesive layer, and a release liner having irregularities formed on the surface adjacent to the pressure-sensitive adhesive layer, have in this order. In the pressure-sensitive adhesive sheet of the present invention, one of the protective layer-side and release liner-side surfaces in the lamination direction has undulations with a larger amplitude than the other release liner-side surface. The other surface on the release liner side is in a smooth state in which the amplitude of undulation is suppressed as compared to the one surface.

Of the two surfaces of the pressure-sensitive adhesive sheet having the above structure, the release liner side is in a smooth state with less waviness compared to the protective layer side. Even if it is formed, the difference in thickness depending on the location is small, and it is easy to cut at an appropriate depth.

In addition, according to the pressure-sensitive adhesive sheet having the above structure, even if the smooth surface on the release liner side of one pressure-sensitive adhesive sheet is adjacent to the surface on the protective layer side of the other pressure-sensitive adhesive sheet when the pressure-sensitive adhesive sheets are superimposed on each other, Since the surface on the protective layer side is in a rough state, the adhesive sheets are in close contact with each other and are difficult to stick together, thereby preventing blocking.

It is a figure which shows the adhesive sheet of embodiment. FIG. 4 is a partially enlarged view showing an example of the surface of the pressure-sensitive adhesive sheet including undulations; FIG. 4 shows the adhesive sheets of the embodiment to be superimposed.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and differ from the actual ratios.

As shown in FIG. 1, the adhesive sheet 100 of the embodiment has a process film 110 (protective layer), a coat layer 120, a base layer 130, an adhesive layer 140, and a release liner 150 in this order in the stacking direction. The adhesive sheet 100 is not particularly limited, but is, for example, a decorative sheet such as a blackout tape attached to a window frame of a vehicle body or the like.

In the pressure-sensitive adhesive sheet 100, of both surfaces 111 and 151 on the process film 110 side and the release liner 150 side in the stacking direction, one surface 111 on the process film 110 side is rougher than the other surface 151 on the release liner 150 side. is. Conversely, the other surface 151 on the release liner 150 side is smoother than the one surface 111 on the process film 110 side.

Referring to FIG. 2, the rough surface 111 contains undulations with a larger amplitude A than the smooth surface 151, while the smooth surface 151 has a larger amplitude A of undulations than the rough surface 111. suppressed. The surface waviness is represented, for example, by a waviness curve defined in JIS B0601:2013 (ISO 4287:1997). Also, the amplitude A of the undulation is expressed as, for example, the average height Wc of the undulation curve elements defined in the same standard.

On the rough surface 111, the average height Wc of the undulating curve elements is, for example, 5 μm or more, preferably 5 μm or more and 20 μm or less, more preferably 5 μm or more and 10 μm or less.

On the other hand, on the smooth surface 151, the maximum cross-sectional height Wt of the undulation curve is, for example, 0.1 μm or less, and the average height Wc of the undulation curve elements on the surface 151 is, for example, 0.01 μm or more and 0.1 μm or less. be.

The undulation curves of the surfaces 111 and 151 can be measured, for example, with a surface roughness measuring machine Surftest SV-3000 manufactured by Mitutoyo Corporation under the conditions of a cutoff value of 0.8 mm and an evaluation length of 10 mm.

The pressure-sensitive adhesive sheet 100 is produced, for example, by forming the coat layer 120 and the base layer 130 on the process film 110 and bonding a laminate of these to a laminate of the pressure-sensitive adhesive layer 140 and the release liner 150 .

The process film 110 is formed of, for example, polyethylene terephthalate (PET), but is not limited thereto. For example, at least one selected from the group consisting of polyethylene terephthalate (PET), polyolefin, and polyvinyl chloride (PVC). Formed by seeds. Polyolefins include, but are not limited to, polyethylene (PE), polypropylene (PP), polybutene (PB), polybutadiene (PBD), polymethylpentene (PMP), and the like.

In the process film 110, the surface 111 is roughened and is in a matte state, but the opposite surface on the side of the coating layer 120 has a smaller amplitude of undulation than the surface 111 and is preferably smooth.

The coating layer 120 is obtained, for example, by coating a smooth surface opposite to the surface 111 of the process film 110 with a dispersion liquid in which a resin and optionally an additive are dispersed in a solvent, and drying it. be done. The process film 110 is removed from the coat layer 120 when the pressure-sensitive adhesive sheet 100 is actually attached to an adherend. To prevent the surface of a coating film from becoming uneven and a part of the coating film from adhering to other places and being lost.

The function of the coat layer 120 in the pressure-sensitive adhesive sheet 100 is not particularly limited and can be appropriately designed according to the application of the pressure-sensitive adhesive sheet 100. For example, when the pressure-sensitive adhesive sheet 100 is a decorative sheet, , the coating layer 120 is provided to adjust the glossiness.

By forming the coat layer 120 on the smooth surface opposite to the surface 111 of the process film 110, the surface becomes smooth and the glossiness is less likely to be lost. Having a flat and smooth surface is suitable for the decorative sheet.

Examples of the resin constituting the coat layer 120 include polyurethane; acrylic polymer; polyvinyl chloride; polyolefin such as polyethylene and polypropylene; thermoplastic elastomer such as olefin and polyester; can be done. Coat layer 120 may also contain various additives such as pigments, inorganic fillers, organic fillers, and ultraviolet absorbers.

The substrate layer 130 is laminated on the coat layer 120 following the formation of the coat layer 120 . Base material layer 130 preferably contains a colorant and a binder resin. The base material layer 130 is formed by, for example, coating the coat layer 120 with an ink composition containing a colorant, a resin, and optionally a dispersant, a solvent, and the like, followed by drying and curing.

Colorants contained in the base material layer 130 include, for example, carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine smoke, etc.), graphite (graphite), copper oxide, manganese dioxide, and aniline black. , perylene black, titanium black, cyanine black, activated carbon, ferrite (nonmagnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, composite oxide black pigment, anthraquinone organic black pigment etc. are used.

Examples of the resin contained in the base layer 130 include polyvinyl chloride resin, polyurethane resin, acrylic resin, and polyolefin resin.

The adhesive layer 140 is not particularly limited, and is formed of, for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive, or the like. These adhesives may be used singly or in combination of two or more. Moreover, the adhesive may contain a cross-linking agent. The adhesive layer 140 is obtained, for example, by applying an adhesive composition to the release liner 150 and then drying. The thickness of the adhesive layer 140 is, for example, 10 μm or more and 100 μm or less, but is not limited thereto.

The release liner 150 has unevenness 152 on the surface adjacent to the adhesive layer 140 . The release liner 150 has a first polyolefin resin layer 153 with irregularities 152 formed thereon, a support substrate 154, and a second polyolefin resin layer 155 in this order in the stacking direction.

The thickness of the first polyolefin resin layer 153 is, for example, 10 μm or more and 50 μm or less, but is not limited to this. The thickness of the support base material 154 is, for example, 10 μm or more and 250 μm or less, but is not limited thereto. The thickness of the second polyolefin resin layer 155 is, for example, 10 μm or more and 50 μm or less, but is not limited thereto.

The unevenness 152 is composed of, for example, a plurality of ridges linearly extending along the surface of the release liner 150 , the ridges being convex and the gaps between the ridges being concave. In the unevenness 152, the height of the convex portion and the depth of the concave portion are, for example, 5 μm or more and 20 μm or less, but are not limited thereto.

The convex ridges are, for example, triangular, rectangular, trapezoidal, polygonal with rounded vertices, or substantially half-shaped in a cross section perpendicular to the direction extending along the surface of the release liner 150 . Although it has a cross-sectional shape such as a circular shape, the cross-sectional shape in the same cross section is not limited to these, and can be designed as appropriate.

In addition, there is no particular limitation on how the ridges extend in a plan view seen in a direction perpendicular to the surface of the release liner 150. For example, they may extend linearly or curvedly. It may be bent and extended. Also, the ends of the linearly extending ridges preferably reach the edges of the release liner 150 .

In addition, when viewed from the same plane, the plurality of ridges may be parallel or may cross each other, and they exhibit a geometric pattern such as a grid pattern. It is not limited to the form of presenting, and may be a form provided irregularly.

As a result of the shape of the unevenness 152 described here being inverted and transferred to the adjacent adhesive layer 140 , grooves are formed in the adhesive layer 140 . Since this groove discharges air that enters between the adherend and the pressure-sensitive adhesive layer 140 during application, swelling is suppressed.

It should be noted that the irregularities 152 are not limited to the form formed by linearly extending protrusions as described above. Concavities of different sizes, such as depth and opening size, may be arranged randomly. Alternatively, the unevenness 152 may be configured by combining at least two different constituent elements such as linearly extending ridges, island-like scattered protrusions, and depressions.

The configuration of the unevenness 152 depends on what function is mainly given to the adhesive layer 140. As described above, the unevenness 152 preferably includes linearly extending ridges so that a is formed.

On the other hand, for example, if the surface roughness of the pressure-sensitive adhesive layer 140 is mainly intended to be increased in order to reduce the contact area with the adherend during alignment, the irregularities 152 are formed by chaotically connected large and small depressions. You may do so.

The unevenness 152 is formed by, for example, embossing the surface of the first polyolefin-based resin layer 153, but is not limited to this, and may be formed by, for example, a printing technique such as screen printing.

The first polyolefin-based resin layer 153 contains polyolefin resin as the main component of the resin in the layer. Here, the main component refers to a resin containing 60% by mass or more (upper limit 100% by mass) relative to the resin, preferably 75% by mass or more (upper limit 100% by mass), and 85% by mass or more (upper limit 100% by mass). % by mass), and most preferably at least 95% by mass (upper limit of 100% by mass).

Polyolefin resins include polyethylene resins and polypropylene resins, and from the viewpoint of embossability, polyethylene resins are preferred.

Polyethylene resins include (branched) low density polyethylene resins (LDPE), linear low density polyethylene resins (LLDPE), medium density polyethylene resins (MDPE), very low density polyethylene resins (VLDPE), high density polyethylene resins (HDPE). ). A mixture of the above polyethylene resins may also be used.

In the first polyolefin resin layer 153, the surface on the adhesive layer 140 side may be treated with a release agent. Examples of the release agent include rubber elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, butadiene-based resins, long-chain alkyl-based resins, long-chain alkyl acrylate-based resins, alkyd-based resins, fluorine-based resins, and the like. mentioned.

The support base material 154 is not particularly limited, but is preferably a plastic film from the viewpoint of smoothness. Examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, and plastic films such as polyolefin films such as polypropylene and polyethylene. Among these, the support base material 154 is preferably a polyethylene terephthalate film because of its high flexural rigidity. The polyethylene terephthalate film is preferably biaxially oriented because it is resistant to shrinkage and has high flexural rigidity.

Like the first polyolefin resin layer 153, the second polyolefin resin layer 155 contains polyolefin resin as the main component of the resin in the layer. The second polyolefin resin layer 155 may have the same composition as the first polyolefin resin layer 153, or may have a different composition.

Next, the effect of this embodiment is described.

When the pressure-sensitive adhesive sheet 100 of this embodiment is attached to an adherend, the release liner 150 is partially peeled off, and the exposed part of the pressure-sensitive adhesive layer 140 is temporarily attached to the adherend so as to facilitate alignment. be stopped. Therefore, the release liner 150 is slit so that it can be partially peeled off.

The cut is made by pressing a blade against the surface 151 of the release liner 150. Unlike the present embodiment, if the surface 151 is not smooth and is roughened like the surface 111 and includes undulations with a large amplitude, Due to the undulations, the thickness of the release liner 150 varies greatly depending on the location, which may make it difficult to cut at an appropriate depth.

For example, when the depth of the cut is set with reference to a relatively thick portion of the release liner 150, if the actual cut portion is a relatively thin portion, the cut will be too deep. , blade marks remain on the adhesive layer 140 and the base material layer 130, and as a result of these marks being visible from the surface of the adhesive sheet 100, there is a risk that the appearance will be impaired.

Further, when the depth of the cut is set based on the relatively thin portion of the release liner 150, if the actual cut portion is a relatively thick portion, the cut becomes shallow. There is a risk that the release liner 150 will not be cut, making partial release difficult.

On the other hand, in the pressure-sensitive adhesive sheet 100 of the present embodiment, since the surface 151 is in a smooth state with less waviness compared to the surface 111, the release liner 150 has a small difference in thickness depending on the location, and an appropriate depth. It is easy to make notches with

The operator peels off a part of the cut and divided release liner 150, temporarily attaches the adhesive sheet 100 to the adherend, and after alignment, peels off the remaining release liner 150 and sticks it to the adherend. The entire sheet 100 is attached.

When the adhesive sheet 100 is wound into a roll from a long state or laminated into a plurality of sheets, the adhesive sheets 100 overlap each other, for example, when the adhesive sheet 100 is transported or stored.

At that time, as shown in FIG. 3, the adhesive sheets 100 are superimposed so that the smooth surface 151 of one adhesive sheet 100 is adjacent to the surface 111 of the other adhesive sheet 100. In contrast, if the surface 111 is as smooth as the surface 151, the adhesive sheets 100 may adhere to each other and become difficult to separate, resulting in blocking.

On the other hand, in the present embodiment, since the surface 111 is in a rough state, even if the surface 151 is smooth, the pressure-sensitive adhesive sheets 100 are hard to adhere to each other and blocking is prevented.

Unlike the present embodiment, the release liner 150 may be formed of a single layer of resin such as polyethylene terephthalate (PET). However, since the release liner 150 has a configuration in which the first polyolefin resin layer 153, the supporting base material 154, and the second polyolefin resin layer 155 are laminated in this order, the irregularities 152 are easily formed, and the peeling Curling of the liner 150 can be suppressed.

Specifically, the first polyolefin-based resin layer 153 is mainly composed of polyolefin resin, and is superior in workability compared to resin such as polyethylene terephthalate (PET), so that the irregularities 152 are easily formed.

In addition, since the second polyolefin resin layer 155 is arranged on the side opposite to the first polyolefin resin layer 153 with respect to the support substrate 154, curling of the release liner 150 is easily suppressed. From the viewpoint of suppressing curling of the release liner 150 , the second polyolefin resin layer 155 preferably has the same composition as the first polyolefin resin layer 153 .

Further, the second polyolefin-based resin layer 155 is excellent in workability like the first polyolefin-based resin layer 153, so that the surface 151 can be easily smoothed, which is preferable.

If the maximum cross-sectional height Wt of the undulating curve defined in JIS B0601:2013 (ISO 4287:1997) on the surface 151 is 0.1 μm or less, the thickness of the release liner 150 varies depending on the location. , it is easy to make a cut at a more appropriate depth.

Further, if the average height Wc of the undulating curve elements defined in JIS B0601:2013 (ISO 4287:1997) on the surface 111 is 5 μm or more, the adhesion between the overlapping adhesive sheets 100 is particularly effectively suppressed. Therefore, blocking is more likely to be prevented.

The present invention is not limited to the embodiments described above, but can be variously modified within the scope of the claims.

For example, the shape of the pressure-sensitive adhesive sheet is not particularly limited, and may be long or may be cut into a shape corresponding to the adherend. In addition, the pressure-sensitive adhesive sheet may contain other layered constituent elements in addition to the constituent elements disclosed in the above embodiments.

100 adhesive sheet,
110 process film (protective layer),
111 one surface on the process film side (one surface on the protective layer side),
120 coat layer,
130 base layer,
140 adhesive layer,
150 release liner,
151 the other side of the release liner,
152 Unevenness,
153 first polyolefin resin layer,
154 supporting substrate,
155 second polyolefin resin layer,
A Amplitude of swell.

Claims (5)

A protective layer, a coat layer, a base layer, an adhesive layer, and a release liner having irregularities formed on a surface adjacent to the adhesive layer in this order in the stacking direction,
Of both the protective layer side and the release liner side in the lamination direction,
One surface on the protective layer side is in a rough state including undulations with a larger amplitude than the other surface on the release liner side,
wherein the protective layer is a process film;
The pressure-sensitive adhesive sheet, wherein the other surface on the release liner side is smoother than the one surface with an amplitude of undulation being suppressed. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the release liner has the first polyolefin resin layer on which the irregularities are formed, a support substrate, and a second polyolefin resin layer in this order in the stacking direction. 3. According to claim 1 or claim 2, wherein the maximum cross-sectional height Wt of the undulating curve defined in JIS B0601:2013 (ISO 4287:1997) is 0.1 μm or less on the other surface on the release liner side. Adhesive sheet described. The one of claims 1 to 3, wherein the average height Wc of the undulating curve elements defined in JIS B0601:2013 (ISO 4287:1997) on the one surface on the protective layer side is 5 μm or more. The pressure-sensitive adhesive sheet according to any one of the above. forming a laminate having a process film, a coat layer, a base layer, an adhesive layer, and a release liner having irregularities formed on a surface adjacent to the adhesive layer in this order in the lamination direction;
At this time, of both surfaces on the process film side and the release liner side in the lamination direction,
One surface on the process film side is in a rough state including undulations with a larger amplitude than the other surface on the release liner side, and the other surface on the release liner side is the one surface. It is a smooth state in which the amplitude of the swell is suppressed,
A method for producing a pressure-sensitive adhesive sheet, comprising then removing the process film from the laminate.

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